NO170821B - PROCEDURE FOR CLOSELY JOINING A SHELF AND A UNDERWATER'S RANGE AT GREAT DEPTH - Google Patents

Abstract

Method for joining a sleeve (1) and a subsea strut (2) at great depth, comprising forming a series of grooves {4) on the inside of the sleeve, filling each groove with two half-rings (6) of a material which collapses under high pressure, by up to 70? » volume change,. and that the sleeve is placed on the pipe, and that the pipe is expanded so that annular areas of the pipe partially protrude into the grooves.

Description

Porous molded bodies for the production of

ceramic moldings.

Porous bodies find extensive use in technology. A distinction is made between bodies with closed pores, which are required in heating and cooling technology, and bodies with open pores, which make the bodies permeable to gas and liquids and serve as filters and suction bodies. The invention relates to these latter bodies.

Permeable bodies, i.e. bodies equipped with open pores, are e.g. sintered metals and sintered porcelain. These are already suitable, due to the difficulty and complexity of their manufacture, only for limited use.

The invention therefore relates to a mechanically and possibly also chemically resistant porous molded body for the production of ceramic molded bodies, especially in the casting process, using hydraulic pressure, and the molded body is characterized by the body's open pores being filled with intrinsically porous substances.

Such intrinsically porous substances occur, such as e.g. diatomaceous earth, as silicate in nature, or they are produced in different ways from the desired substances with the possibly desired pore sizes and corresponding grain sizes, as they e.g. are used as so-called K.C. dry beads of SiO2 in connection with specific additions of AlgO^ in the chemical industry. Furthermore, painted, e.g. ceramic, porous masses.

The porosity of the bodies constructed according to the invention can be strongly determined and controlled by choosing the pore-filling material. One therefore starts from a measurable pore size in the material, from the choice of grain size and allocation ratio to carrier material as desirable determinable sizes and adapts to any requirements. This is a significant advantage over all known pore-forming methods which cannot be controlled in this way.

A further advantage lies in the fact that, according to the invention, one is not directed to sintering methods either, but rather can proceed at room temperature, using self-binding or self-hardening substances as carriers, such as cement, especially clay cement, or hardened plastics such as duroplast, for which they Porous substances equipped with inherent porosity are added in each time selected quantities and grain sizes already during production. These grains themselves form the pore space in the carrier mass, which they require. You can also add them as a propellant and choose the quantity so that an open porosity of the body to be produced is achieved. This thus consists of a supporting skeleton of mechanically and, if necessary, also chemically resistant substances, such as cement or duroplast, which are filled with inherently porous bodies. Thus, both the mechanical and chemical requirements as well as the porosity itself can be selected as desired.

Different applications are given for such bodies according to the invention, e.g. they are suitable because they are resistant and absorbent, preferably as a wet press form. Ceramic press bodies, e.g. the roof, was previously pressed in plaster molds and with a plaster stamp, which was fully soaked with water so that the molded bodies can be detached from the mold undamaged. Plaster molds, however, have no lifespan and are expensive. You can't get out so well with iron molds, because they have to be lubricated with oil, and because of the oil, folds occur. This disadvantage is avoided by the application according to the invention.

Plastic press molds made of plastic are known. Instead of oil and water, rinse aid must be used here. A shaped body according to the invention can e.g. consist of porous duroplast, and the pores can be filled with separating agents.

But also moulds, especially for casting ceramic bodies from clay emulsions and which act as filters, are preferable for use according to the invention. Due to the great mechanical strength, it can be worked under high clay emulsion pressure. The solvent, in this case water, penetrates in seconds through the pores which are already filled with water for the mould, and can now be used as a dipping mould. The hollow form is surrounded on one side with clay emulsion and on the other side with water. The mold body is formed in the pressure drop between both sides of the dipping mold 6. When the mold is finished, the clay emulsion is raised by the pressure that loads it and completely out. From the water side of the diving mold, water is now fed through the mold in the opposite direction, so that the ceramic mold body loosens very easily and quickly.

Porous bodies according to the invention can, with their absorbent capacity, be used in a dry state and here e.g. replace gypsum in all applications in the area of ceramics with great advantage, as gypsum in almost all cases does not have sufficient hardness. The Mohs hardness for plaster is 2, while e.g. a porous body according to the invention, made of 85% by weight clay cement and 15% by weight diatomaceous earth with a free pore space of 4-1 f° has a hardness between 5°g 6. For example, such a body is produced so that the two substances are weighed and moistened with water until a tough, moldable slurry of high viscosity is formed. This chewy porridge is ground in a colloid mill for 10 minutes. In this grinding process, the diatomaceous earth and the clay melt cement are brought to an approximately equal average grain size and mixed homogeneously at the same time. After the grinding process, the homogeneous porridge is poured into a mold and cured under high humidity and constant wetting for three days.

Pressable granular synthetic resins, e.g. on an epoxy basis or also duroplast with particularly high admixtures of intrinsically porous fillers leads to very firm and in any porosity desired filter bodies or the like.

The drawing shows embodiments according to the invention.

Fig. 1 shows, in strong magnification, a section through the mass of bodies 1. The light-colored material 3 equipped with pores shown as dots is absorbed in the skeleton-like branched structure of the carrier material 4 shown dark. Fig. 2 shows a section through a porous body with open empty pores 2 in an already known embodiment. Fig. 3 is a schematic representation of the pressing device for ceramic pressing compounds using the mold 6 according to the invention, which consists of a matrix and a stamp. The device consists of the vessel 5 > in which the matrix 6 is inserted while pushing against a coarse sand filling 7- The lid of the vessel 5 is, as usual, arranged to carry out the pressing process. Here, too, the piston mold 6 is underpinned with coarse sand 7* Through pipe connections 10, the supply to both mold parts is ensured with water from the container 9 for constant moist retention. This is necessary in order for the mold body 8 to loosen easily.

In fig. 4 shows a filter device or a mold device in section. The vessel 5 occupies the filter 6 in itself. The cavity 12 is used for filling clay emulsion or another emulsion. If it only depends on the filter effect, first the vessel 5 becomes empty and can be emptied via a tap not shown. However, if you want to form a ceramic body in the filter 6 from the clay emulsion by depositing clay on the filter wall, then the vessel 5 is filled with water using the storage container 11 above the supply 10, so that the filter body 6 acts as a dip mold. The mold is formed faster the higher the pressure exerted on the clay emulsion. It therefore depends on the pressure drop that the liquid causes on the two sides of the dip mold.

5a denotes the space filled with coarse sand or gravel between the outer steel jacket 5 and the actual mold body 6. 14 denotes the seal for the upper part to be attached.

After completion of the molding process, the clay emulsion is removed and water is pressed in the opposite direction by means of static pressure through the filter mold so that the molded body will loosen easily.

The invention also relates to the production of molds which are particularly suitable in the ceramic industry, both for the casting process and for the pressing process.

The moldings are preferably self-cast as the self-hardening substances that form the molding, preferably cement, are mixed with pore-filling, intrinsically porous substances, preferably diatomaceous earth, to form a castable aqueous emulsion. The more complicated the shape to be cast, the thinner the emulsion must be, and the greater the risk of separation.

In the chosen example with cement and diatomaceous earth, the latter is quickly driven upwards in the emulsion due to its much lower specific weight, as the cement's degradation process only later thickens. This delay is too great to ensure uniform pore formation over the entire mold.

The invention is based on the task of preventing this harmful separation.

The solution to the task consists in adding such agents to the emulsion which cause a rapid thickening after casting when the emulsion contains substances of very different specific weights.

If, for example, instead of diatomaceous earth, a powder of sintered metal is used for this purpose, then, due to its higher specific gravity, this will tend to settle on the bottom.

The risk of separation is least when there is e.g. substances of approximately the same specific gravity are added, e.g. fine-grained sinter ceramics for the cement.

For each specialty in the mold that conforms to the shape of the ceramic body, its crucible thickness, e.g. in the case of electrical or sanitary ceramics, it is possible to determine empirically favorable compositions and conditions within a wide range.

Portland cement e.g. gives compared to clay soil cement the advantage of having a very gin and hard surface and a fast setting. Depending on the requirements, you can therefore choose Portland cement as the main component and add smaller quantities, e.g. up to 5% > clay soil cement or to proceed in reverse and to use clay soil cement with minor additions of Portland cement. Experiments have shown that clay cement is particularly suitable for achieving the desired porosity and that it can be achieved that it becomes viscous more quickly. Both extremities contribute significantly to the mixture with diatomaceous earth quickly becoming viscous and counteracting separation.

Of particular advantage is a minor addition of binders, especially of thixotropic substances such as e.g. alginates, especially when you want to work with complicated shapes very thin, i.e. with a lot of water added. Here the danger is particularly great, for the light diatomaceous earth to accumulate in the upper areas of the mold and destroy the evenness of the porosity.

Alginates are known to be thixotropic. They ensure rapid thickening. This process is reversible, so that you have a further advantage, e.g. by storing a thickened soln.

ning e.g. by impact again to make it thinner. At standstill, the solution gels again and prevents separation.

A mixture that is particularly suitable for the production of the shaped body consists of approx. " JO % Portland cement and 3>5 f° clay soil

cement with approx. 25% diatomaceous earth with the addition of 0.5 - 0.6%

sodium or ammonium alginate.

After the cement has set, the alginates do not disturb the porosity. They liquefy under pressure and allow themselves to drift out.

When multiple part molds are required, it is advantageous

to equip the limiting edges with an even harder material, preferably with strips or strips of sintered metal, whose open porosity corresponds to that of the other form material. Such strips or strips can already be incorporated during the production of the molded parts.

Claims (7)

1. Porous shaped bodies for the production of ceramic shaped bodies, especially in the casting process using hydraulic pressure, characterized in that the open pores (2) of the body (1) are filled with intrinsically porous substances (3). 2. Porous bodies according to claim 1, characterized in that the porous body (1) consists of substances (4) which provide mechanical and, if necessary, chemical strength and that the pore-filling in and of themselves porous substances (3) are mixed into it to the desired porosity of the body (1) corresponding to the grain size, amount and inherent porosity of the body (1)'s design. 3. Porous bodies according to claim 1, characterized in that the porous body (1) consists of self-hardening or binding substances (4)3 e.g. cement, especially clay cement or curing plastics, especially duroplast, to which pore-forming and pore-filling intrinsically porous substances (3) are mixed before shaping the body (1). 4. Method for the production of pressure-resistant, open-pore forms or filters for plastic masses according to claims 1-3j where the pores are filled with intrinsically porous substances, characterized in that a castable mixture of a self-hardening carrier material, preferably cement with intrinsically porous substances, preferably diatomaceous earth, is equipped with the addition of agents that prevent separation. 5. Method according to claim 4> characterized in that a small addition of thixotropic substances, especially alginates, is mixed into the moldable mixture. 6. Method according to claim 4j, characterized in that Portland cement is used as carrier material with an addition of a few percent clay cement. 7. Method according to claim 4> characterized in that clay soil cement is used as carrier material with an addition of a few percent Portland cement.